Valve sends along an
image
of the redesigned Steam Controller, showing an array of buttons in the area
formerly occupied by the touch screen display. They say they will be giving
hands on demonstrations of this at the upcoming Game Developers Conference.

Steam controller FAQCan I use a controller if I don’t have a Steam machine? Yes. It’ll work very well with any version of Steam.

IGN.comThe Steam Controller is compatible with both Steam Machine and PCs running Steam. Though the controller can be used to play non-Steam games on PC, functionality is very limited.

IGN.com articleWithout Steam, if you plug this into one of those devices and run some game that’s not part of Steam, you would only get the most basic functionality. It wouldn’t actually be very valuable as a controlling device.